抄録
In order to find a possibility of earth-origin electromagnetic (EM) pulses as a precursor of earthquakes, we attempted to obtain spatial distributions of source locations of many EM pulses detected two days before earthquakes. In this paper, we first introduce the procedure for obtaining their source locations, which consists of determinations of exact arrival directions of the EM pulses, estimations of their propagation distances and identifications of their source locations. In deriving a spatial distribution of their locations, we found that the EM pulse sources had been drifting during the period of about 6 hours. The area of the spatial distribution of their source locations was rather small but far from the earthquake epicenter. The spatial difference between the EM pulse source locations and the earthquake epicenter is discussed from view points of conditions for excitations and propagations of EM pulses.
